CN111102064A

CN111102064A - Method for operating an internal combustion engine system

Info

Publication number: CN111102064A
Application number: CN201911023184.2A
Authority: CN
Inventors: 迈克尔·比尔克勒; 哈特穆特·魏斯
Original assignee: Bosch Mahle Turbo Systems GmbH and Co KG
Current assignee: BMTS Technology GmbH and Co KG
Priority date: 2018-10-26
Filing date: 2019-10-25
Publication date: 2020-05-05
Also published as: EP3650677A1; US11111844B2; EP3650677B1; US20200131981A1; DE102018218406A1

Abstract

The invention relates to an internal combustion engine system (1) having a pollutant conversion device (11) and an exhaust gas turbocharger (6) comprising a variable turbine geometry (15) and a wastegate valve (13). Improved environmental balancing and/or increased efficiency of the internal combustion engine system (1) is achieved in that: when the pollutant conversion device (11) has a temperature below a threshold temperature, the variable turbine geometry (15) of the exhaust gas turbine booster (6) is adjusted to a heating position (34), wherein the heating position (34) is such that the variable turbine geometry (15) at the heating position (34) forms a total cross section through which the exhaust gas can flow, which is smaller than a possible control minimum of the total cross section in the control mode (26). The invention also relates to an internal combustion engine system (1) operating in this way.

Description

Method for operating an internal combustion engine system

Technical Field

The invention relates to a method for operating an internal combustion engine system having an internal combustion engine, an exhaust gas turbocharger and a pollutant conversion device. The invention also relates to an internal combustion engine system operating in this way.

Background

The improvement in efficiency and reduction in pollutant emissions play an important role in the development of internal combustion engine systems.

With regard to the increase in efficiency, it is known to use an exhaust-gas turbocharger which comprises a turbine wheel which is integrated in an exhaust-gas device of the internal combustion engine system and which is driven by exhaust gas from the internal combustion engine, and a compressor wheel which is integrated in a fresh-air device of the internal combustion engine system in order to compress fresh air which is supplied to the internal combustion engine. For regulating exhaust-gas turbochargers, it is customary to use wastegate valves and/or variable turbine geometries which are able to vary the effect on the turbine wheel with the exhaust gas.

Pollutant conversion devices are commonly used for reducing pollutant emissions, and the pollutant conversion devices in exhaust gas plants result in a reduction of pollutants in the exhaust gas. Such pollutant conversion devices typically have a threshold temperature above which the pollutant begins to diminish. Below this threshold temperature, the contaminants are not reduced or are reduced less in the contaminant conversion device than the threshold temperature. Therefore, if the temperature in the pollutant transforming device is below the threshold temperature, the proportion of pollutants in the exhaust gases increases, which leads to a worse environmental balance of the combustion engine system.

Such an internal combustion engine system is known from EP 1243767 a 2. The exhaust-gas turbocharger here comprises a wastegate valve which is adjustable and, in the bypass position, leads the exhaust gas via a bypass channel past the turbine wheel. At the bypass position of the wastegate valve, the exhaust gas reaches the pollutant transforming device arranged downstream of the bypass passage at an increased temperature therefrom, so that the pollutant transforming device at this position of the wastegate valve reaches the threshold temperature more quickly.

A similar approach is sought in DE 19833619 a 1. In this internal combustion engine system, two bypass passages that bypass the turbine wheel are provided, wherein in one of the bypass passages, a primary catalyst is arranged in addition to the pollutant transforming device arranged downstream of the bypass passage.

EP 1396619 a1 has disclosed an internal combustion engine system which essentially corresponds to the internal combustion engine system shown in EP 1243767 a2, with the difference that the exhaust gas turbocharger is also provided with a variable turbine geometry. To bring the pollutant converting device to the threshold temperature, the wastegate valve is adjusted to the bypass position.

Disclosure of Invention

The object of the present invention is to provide an improved or at least further embodiment of a method for operating an internal combustion engine system and an internal combustion engine system operated in this way, which is characterized in particular by an increased efficiency and/or an improved environmental balance.

According to the invention, this object is achieved by the subject matter of the independent claims. Advantageous embodiments are the subject of the dependent claims.

The invention is based on the general idea of closing the variable turbine geometry of the exhaust gas turbocharger in an internal combustion engine system comprising the internal combustion engine and the exhaust gas turbocharger as well as the pollutant transforming device by a minimum position of the variable turbine geometry, which minimum position defines a minimum throughflow of the variable turbine geometry, being set in the control mode to reach a threshold temperature of the pollutant transforming device in order to further reduce, in particular to block, the throughflow through the turbine. Thus, the exhaust gas with increased enthalpy reaches the pollutant transforming device, in particular due to the reduction/absence of heat losses and/or kinetic energy losses upon impact with the turbine wheel, so that the pollutant transforming device reaches the threshold temperature more quickly. The threshold temperature here defines a temperature of the pollutant converting device above which a reduction in the pollutant occurs in the pollutant converting device and/or below which a reduction in the pollutant or no reduction in the pollutant occurs. By means of the solution according to the invention, the pollutant converting device achieves a pollutant reduction faster, and thus less pollutants are discharged, thereby achieving an improved environmental balance of the combustion engine system. The faster reaching of the threshold temperature also enables the exhaust gas turbocharger to operate faster in the control mode, in particular to accomplish a faster replenishment/compression of the fresh air to be supplied to the combustion engine, thereby improving the efficiency of the combustion engine system.

In accordance with the inventive idea, an internal combustion engine system comprises an internal combustion engine, an exhaust gas turbocharger and a pollutant transforming device. The internal combustion engine system further comprises a fresh air device for supplying fresh air to the internal combustion engine and an exhaust gas device for discharging exhaust gases. In addition to the turbine wheel, the exhaust-gas turbocharger comprises a compressor wheel integrated in the fresh air device for compressing fresh air, which compressor wheel is driven by the turbine wheel integrated in the exhaust-gas device. The exhaust gas turbocharger also includes an adjustable wastegate valve that is adjustable between a closed position and an open or bypass position. When the wastegate valve is in the bypass position, exhaust gas is directed to bypass the turbine wheel via the bypass passage. The pollutant converting device is used for reducing pollutants in the exhaust gas and is conveniently integrated in the exhaust gas unit. The pollutant converting device has a threshold temperature above which pollutants in the pollutant converting device are reduced. The variable turbine geometry of an exhaust-gas turbocharger comprises guide elements which surround the turbine wheel in the circumferential direction and are adjustable, wherein the guide elements are arranged to follow one another in the circumferential direction, forming at each location a total cross section through which exhaust gas can flow. In a control mode of the internal combustion engine system, the pollutant transforming device has a temperature above a threshold temperature and the variable turbine geometry is operated such that the guiding element forms a total cross-section between a control minimum and a control maximum. In the control mode, the total cross section corresponds at least to a control minimum. The corresponding position of the variable turbine geometry is also referred to as the so-called minimum flow position. According to the invention, the internal combustion engine system is operated in the heating mode conversely if the temperature of the pollutant transforming device is below the threshold temperature. In contrast to the control mode, the variable turbine geometry is adjusted in the heating mode by the guide elements in such a way that the total cross section formed by the guide elements is smaller than the control minimum. Thus, no exhaust gas or at least a reduced specific gravity of the exhaust gas reaches the turbine wheel, thereby reducing the loss of the corresponding enthalpy of the exhaust gas, in particular heat loss. Thus, the exhaust gas with increased enthalpy reaches the pollutant converting device, in particular at an increased temperature, so that the pollutant converting device reaches the threshold temperature more quickly. The reduced exhaust gas flow to the turbine wheel also causes the compressor wheel to create greater resistance to the fresh air flowing through the fresh air device, particularly acting as a restrictor. This leads, in particular without further measures, to an increase in the specific gravity of the fuel in the mixture of fresh air and fuel which is fed to the internal combustion engine. The unburned fuel is subsequently burned in the exhaust means, in particular in the pollutant converting device, as a result of the higher specific gravity of the unburned fuel reaching the exhaust means. Thereby also accelerating the heating of the pollutant converting device.

In contrast to the variable turbine geometry known from the prior art and the method for operating the same, in which the guide element at its individual positions forms a total cross section for the exhaust gas flowing toward the turbine wheel, which does not fall below a minimum value corresponding to a control minimum in order to always allow the exhaust gas to leave the internal combustion engine and thus to be able to operate the internal combustion engine, in particular when the internal combustion engine is idling, the respective position of the control minimum/guide element (also referred to as the minimum flow position) is maintained in the control mode and is not reached, in particular is reduced to zero, in the heating mode. This results in the pollutant converting device heating up more quickly in the heating mode.

The pollutant-converting device is advantageously arranged downstream of the turbine wheel of the exhaust-gas turbocharger. In this way, in the control mode, the exhaust gas with increased enthalpy reaches the turbine wheel, thereby operating the exhaust gas turbocharger more efficiently.

The pollutant converting device is conveniently arranged downstream of the bypass channel of the exhaust apparatus. The exhaust gas which bypasses the turbine wheel via the bypass channel also reaches the pollutant converting device.

The wastegate valve is conveniently adjustable between a bypass position, in which the bypass passage is closed and exhaust gas flows towards the turbine wheel, in particular via a variable turbine geometry, and a closed position.

The control minimum/associated position of the guide element, in particular the so-called minimum flow position, corresponds to the total cross section which allows/ensures the operation, in particular the acceleration, of the internal combustion engine in the control mode.

The pollutant converting device is preferably designed to reduce pollutants in the exhaust gas by conversion. This is preferably done by reaction of components contained in the exhaust gas and/or components introduced in the exhaust gas. In particular, oxidation and/or reduction reactions are used here. The pollutant-converting device preferably comprises a catalyst for this purpose, which catalyst sets, in particular corresponds to, the threshold temperature/operating temperature. The threshold temperature advantageously corresponds to an operating temperature of the pollutant converting device, in particular of the catalyst, below which the conversion rate of the pollutant converting device is greatly reduced. Alternatively, the threshold temperature may correspond to a start-up temperature of the pollutant converting device, in particular the catalyst, above which conversion of the pollutant is started or initiated.

The pollutants are mainly carbon monoxide, nitrogen oxides (also referred to as NOx), and the like.

When the pollutant converting device, in particular a catalyst of the pollutant converting device, has a temperature below a threshold temperature, a heating mode of the internal combustion engine system is achieved as described above. This is especially true during cold start of an internal combustion engine system, where the pollutant converting device is at ambient temperature. It is conceivable that the temperature of the pollutant transforming device, in particular the catalyst, falls below a threshold temperature when the combustion engine system is running, in particular when it is idling and/or when the ambient temperature is very low. Even in these cases, the internal combustion engine system can transition to the heating mode.

The internal combustion engine system is conveniently operated in the control mode when the pollutant converting device reaches and/or exceeds the threshold temperature.

As long as the guide elements of the variable turbine geometry are adjustable, they can in principle be designed arbitrarily around the turbine wheel and form, at their respective locations, a total cross section for the exhaust gas to flow through towards the turbine wheel. The guide elements are advantageously formed as guide vanes.

In the heating mode, the embodiment with a closed variable turbine geometry is advantageous, so that the guide elements form a closed surface in the circumferential direction, irrespective of the respective tolerances. Thus, no exhaust gas flows to the turbine wheel, regardless of the tolerances and/or undesired leakage. Thereby maximizing the specific gravity of the exhaust gas flowing to the pollutant converting device and thereby reaching the threshold temperature more quickly. Conveniently, in this case the wastegate valve is adjusted to a bypass position in order to ensure that the exhaust gas flows as unobstructed as possible to the pollutant converting device. In this way, sufficient exhaust gas emission from the internal combustion engine is also ensured.

Preferably, the waste gate valve preferably releases the flow-through cross-section of the bypass channel to the maximum extent, in particular to the maximum extent/open in the heating mode to ensure that the pollutant converting device is exposed to the bypass mass flow. This results in a minimization of the obstruction, in particular the resistance, of the exhaust gas due to the wastegate valve, so that the exhaust gas with possibly large enthalpy reaches the pollutant transforming device. By "open to the maximum" is therefore meant in particular that the exhaust gas flow can reach the pollutant converting device as unimpeded as possible through the wastegate valve and/or through the bypass channel.

Since in the closed position of the variable turbine geometry the air in the fresh air device is blocked in the heating mode by means of the turbine wheel, the internal combustion engine operates like a suction motor in the heating mode. This is the case in particular when the internal combustion engine is idling.

As the load demand on the internal combustion engine increases, the internal combustion engine system can be conveniently operated in a conventional cold start mode, which means that the wastegate valve and variable turbine geometry are adjusted according to the load demand. In the present case, the load demand is to be understood as the torque available in particular from the internal combustion engine.

Alternatively, it is conceivable to equip the internal combustion engine system with an electric machine, by means of which the air in the fresh air device can be compressed. In this case, the electric machine in operation can drive the compressor wheel of the exhaust-gas turbocharger and/or an additional compressor for compressing air, separate from the compressor wheel. If the load demand of the combustion engine exceeds a threshold value, hereinafter also referred to as first threshold value, the electric machine is operated to compress air in the fresh air device. The first threshold value is expediently selected such that it is above a load requirement which the internal combustion engine is able to provide at the heating position of the guide element and the bypass position of the wastegate valve. In this case, the internal combustion engine system continues to operate in the heating mode and the electric machine is additionally activated in order to meet the load demand above the first threshold by means of compressed air. The motor may be deactivated when the load demand falls below a first threshold.

The preferred embodiment provides that in case of a greater load demand on the internal combustion engine, i.e. when the load demand exceeds a second threshold value, which is greater than the first threshold value, the internal combustion engine system is operated in a normal cold start mode, which means that the wastegate valve and the variable turbine geometry are adjusted according to the load demand, whereby the variable turbine shape is no longer in a fully closed state. The motor may then continue to operate.

If the load demand falls below the second threshold and the pollutant transforming device has a temperature below the threshold temperature, the internal combustion engine system is preferably operated again in the heating mode, wherein the electric machine is operated when the load demand exceeds the first threshold.

When changing from the heating mode to the control mode and/or the normal cold start mode, the wastegate valve and the variable turbine geometry are preferably adjusted such that the torque and the rotational speed of the internal combustion engine follow a process which is as continuous as possible, i.e. a process without jumps. Abrupt or abrupt changes in the operation of the internal combustion engine are thereby avoided or at least reduced. This results in increased comfort for the user of the internal combustion engine.

Likewise, the activation and deactivation of the electric machine, respectively, is preferably carried out in such a way that the torque and the rotational speed of the internal combustion engine follow a process which is as continuous as possible, i.e. a process without jumps. Abrupt or abrupt changes in the operation of the internal combustion engine are thereby avoided or at least reduced. This results in increased comfort for the user of the internal combustion engine.

In a preferred embodiment, the wastegate valve is opened already before starting the internal combustion engine, in particular before cold starting. Alternatively or additionally, the variable turbine geometry is advantageously closed as far as possible, particularly advantageously completely closed, before the internal combustion engine is started, in particular before a cold start. This results in faster and/or more efficient heating in the subsequent heating mode, thereby improving the environmental balance.

A further improvement of the environmental balance of the combustion engine system can be achieved by arranging the auxiliary pollutant reducing device in the exhaust apparatus, in particular upstream of the pollutant converting device, such that the exhaust gas flowing through the bypass flows through the auxiliary pollutant reducing device. To this end, the secondary pollutant reducing device may be arranged in the bypass channel upstream or downstream thereof and upstream of the pollutant converting device. The secondary pollutant converting device is designed such that the operating temperature of the secondary pollutant reducing device is reached more quickly than the threshold temperature of the pollutant converting device. This is achieved in particular by making the secondary pollutant reducing device smaller in size. In particular, the auxiliary pollutant reducing device may comprise a catalyst having a correspondingly smaller size than the catalyst of the pollutant converting device. Thus, a reduction of pollutants in the exhaust gas is achieved before the pollutant converting device reaches its threshold temperature.

It is to be understood that an internal combustion engine system operated in this manner, in addition to a method for operating an internal combustion engine system, also falls within the scope of the present invention.

To this end, the internal combustion engine system may comprise a corresponding control device, which is communicatively connected to the exhaust gas turbocharger, in particular to the variable turbine geometry. The control device is also advantageously communicatively connected to the wastegate valve.

It is conceivable to provide a mechanical stop for the variable turbine geometry, which mechanical stop defines a control minimum in the control mode. In particular, at least one of the guide elements and/or an adjusting device adjusting the guide element impacts the stop, so that the total cross section formed by the guide element cannot fall below a control minimum. The stop is preferably adjustable and in the heating mode is adjusted such that the total cross-section is less than a control minimum at the heating position.

The internal combustion engine system may comprise at least one temperature sensor for determining the temperature of the pollutant transforming device.

Preferably, the variable turbine geometry is designed such that at least two guide elements, preferably all guide elements, which follow each other in the circumferential direction at the heating location, are in contact with each other. By the contact of the guide elements with one another, a section is formed through which the tissue waste gases flow, so that the above-mentioned closed surface is thus preferably formed in the circumferential direction.

In this respect, embodiments have proved advantageous in which, at the heating position, guide elements adjacent in the circumferential direction are superposed on one another. The closed surface is thus enlarged to its maximum extent, so that the exhaust gas flow towards the turbine wheel is prevented more effectively. Such an embodiment is particularly preferred, wherein at the heating position, each guide element is supported with its tip facing a circumferentially adjoining guide element at a circumferentially adjoining trailing end portion of this guide element, wherein the trailing end portion of each guide element is the portion of the guide element remote from the tip of the guide element. This results in a further enlargement of the closure surface.

In the heating position, the tip of the guide element is advantageously located on the surface of the adjacent guide element facing the turbine wheel. This ensures that the heating position, in particular the closing surface, is achieved more reliably.

The internal combustion engine system and associated method of operation can be used in any application. It is conceivable to use the internal combustion engine in a motor vehicle, in particular in addition to an electric drive.

Further important features and advantages of the invention are found in the dependent claims, in the drawings and in the description of the relevant figures with reference to the drawings.

It is to be understood that the features mentioned above and those yet to be explained below can be used not only in the respectively mentioned combination but also in other combinations or alone without departing from the scope of the present invention.

Drawings

Preferred embodiments of the present invention are illustrated in the figures, and will be described in more detail in the following description, in which like reference numbers indicate identical or similar or functionally identical elements.

Schematically showing:

figure 1 is a very simplified circuit diagram type schematic diagram of an internal combustion engine system,

figure 2 is a flowchart for explaining an operating method of the internal combustion engine system,

figures 3 and 4 are plan views of the variable turbine geometry of the internal combustion engine system at different positions respectively,

figure 5 is a very simplified circuit diagram type schematic of an internal combustion engine system in another embodiment,

figure 6 is a very simplified circuit diagram type schematic of an internal combustion engine system in yet another embodiment,

fig. 7 is a flowchart for explaining an operation method of the internal combustion engine system of fig. 5 and 6.

Detailed Description

A very simplified circuit diagram type of internal combustion engine system, as shown in fig. 1, comprises an internal combustion engine 2 having at least one combustion chamber 3, wherein, in fig. 1, the internal combustion engine 2 comprises, by way of example, only four such combustion chambers 3. In operation of the internal combustion engine 2, fresh air is supplied to at least one of the combustion chambers 3 by a fresh air device 4 and mixed with fuel. The fresh air and fuel mixture is at least partially combusted in the combustion chamber 3, so that exhaust gases are generated, which are discharged via an exhaust gas device 5. The internal combustion engine system 1 further comprises an exhaust gas turbocharger 6, which, as is shown symbolically in fig. 1, comprises a turbine wheel 7 integrated in the exhaust gas system 5 and a compressor wheel 8 integrated in the fresh air system 4. The turbine wheel 7 is driven by the exhaust gas and thus drives a compressor wheel 8, which compresses the air in the fresh air device 4. This is achieved, for example, by a shaft 9 of the exhaust-gas turbocharger 6, which connects the turbine wheel 7 and the compressor wheel 8 to one another. In order to cool the fresh air compressed by the compressor 8, a charge air cooler 10 is integrated into the fresh air device 4 downstream of the compressor wheel 8. The internal combustion engine system 1 further comprises a pollutant transforming device 11, which in operation reduces the specific gravity of pollutants in the exhaust gases before they are discharged. The pollutant converting device 11 has a threshold temperature above which the conversion of pollutants in the exhaust gas is initiated or greatly enhanced in the pollutant converting device 11 by reaction of components present in or introduced into the exhaust gas. To this end, the pollutant transforming device 11 preferably comprises a catalyst 12, which specifies or defines said threshold temperature. The threshold temperature thus corresponds to a start-up temperature at which the conversion in the catalyst 12 is carried out or started, and which can be between 200 ℃ and 300 ℃, or up to an operating temperature of the catalyst 12 which is above the start-up temperature and which can be between 300 ℃ and 1000 ℃.

The exhaust-gas turbocharger 6 comprises a wastegate valve 13 which is adjustable between a closed position and a bypass position. At the bypass position of the wastegate valve 13, the exhaust gas is conducted through the turbine wheel 7 via a bypass channel 14 of the waste device, which extends from a branching point 40 arranged upstream of the turbine wheel 7 to a return point 41 arranged downstream of the turbine wheel 7. In the example shown, the pollutant converting device 11 is integrated in the exhaust gas unit 5 downstream of the bypass channel 14. Furthermore, in the example shown, the wastegate valve 13 is arranged in a bypass duct 14. In fig. 1, the exhaust-gas turbocharger 7 also comprises a variable turbine geometry 15, represented by an arrow, which is shown in plan view in fig. 3 and 4. The variable turbine geometry 15 is arranged between a diverging position 40 and a return position 41 outside the bypass channel 14.

The variable turbine geometry 15 therefore comprises a plurality of guide elements 16, which in the example shown each form a guide vane 17. Fig. 3 and 4 show a plan view of the exhaust-gas turbocharger 1 in the axial direction 18 of the shaft 9 and of the turbine wheel 7 in the region of the variable turbine geometry 15, respectively. The guide elements 16 of the variable turbine geometry 15 surround the turbine wheel 7 in the circumferential direction 19 and are each adjustable. Here, between adjacent guide elements 16, in each case a cross section 20 (as shown in fig. 3) is formed through which the exhaust gas can flow toward the turbine wheel 7, wherein the sum of all cross sections 20 defines a total cross section which can be varied by adjusting the guide elements 16. This means that the guide element 16 forms, at its various locations, a total cross section through which the exhaust gas can flow towards the turbine wheel 7. For the adjustable arrangement, the guide elements 16 are each mounted rotatably in a vane ring 21 and the guide elements 16 are adjusted by an adjusting ring 22 of an adjusting device 23, which adjusts the guide elements 16 together.

The internal combustion engine system 1 further comprises a control device 24, shown in dashed lines, which is communicatively connected to the variable turbine geometry 15 and to the wastegate valve 13 for controlling and/or regulating them.

Fig. 2 shows a flow chart of a method for operating the internal combustion engine system 1, which is carried out by means of the control device 24.

In a first method step 25, it is checked whether the temperature of the pollutant converting device 11, in particular the catalyst 12, is above or below a threshold temperature. This check can be carried out by means of a temperature sensor, not shown, or in another way, for example by means of pollutants present in the exhaust gases downstream of the pollutant conversion device 11.

If the pollutant converting device 11, in particular the catalyst 12, has a temperature above a threshold temperature, the internal combustion engine system 1 is operated in the control mode 26. In the control mode 26, the wastegate valve 13 and the variable turbine geometry 15 are adjusted as required, in particular to suit the power requirements of the internal combustion engine 2. In the control mode 26, the variable turbine geometry 15 is set according to the method step 27 shown, so that the guide elements 16 in each position form a total cross section which lies between the control minimum and the control maximum. This means that in the control mode 26 the variable turbine geometry 15 is operated such that the total cross section at least corresponds to a control minimum, thereby ensuring a minimum inflow of the turbine wheel 7.

As shown in fig. 3, said control minimum of the total cross section is formed at a corresponding position 28 of the variable turbine geometry 15. In this position 28, also referred to below as first position 28 or minimum flow position 29, a gap 30, which forms a cross section 20 of the type described, is formed between each of the guide elements 16 and the guide elements 16 adjacent in the circumferential direction. In the control mode 26, the variable turbine geometry 15 can be adjusted or can only be adjusted such that the total cross section corresponds at least to the control minimum established at the first position 18.

The method then returns to the first method step 25, whereby it is rechecked whether the temperature of the pollutant converting device 11, in particular the catalyst 12, is above or below the threshold temperature.

If the temperature of the pollutant converting device 11, in particular the catalyst 12, is below a threshold temperature, the internal combustion engine system 1 is operated in a heating mode 31. In the heating mode 31, the variable turbine geometry 15 is adjusted in a method step 32 such that the total cross section is below a control minimum, i.e. the guide element 16 is more closed than in the first position 28 shown in fig. 3, so that the gap 30 is respectively at least smaller than in the first position 18.

In fig. 4, the respective position of the variable turbine geometry 15, hereinafter also referred to as second position 33 or heating position 34, is shown. At the heating point 34, the exhaust gas with reduced specific gravity flows to the turbine wheel 7. Accordingly, the proportion of the exhaust gas flowing to the pollutant converting device 11 via the bypass passage 14 is increased. Therefore, the enthalpy of the exhaust gas flowing through the pollutant transforming device 11, in particular the catalyst 12, also increases. In particular, this results in a reduction of the loss of thermal and/or kinetic energy due to the throughflow through the turbine wheel 7. Thus, the pollutant converting device 11, in particular the catalyst 12, is heated up faster and reaches the threshold temperature faster. At the heating position 34, the wastegate valve 13 is also adjusted to the bypass position and is opened to its maximum extent, so that the exhaust gas can flow through the bypass channel 14, bypassing the turbine wheel 7 and the variable turbine geometry 15, preferably unimpeded, to the pollutant converting device 11.

When changing from the control mode 26 to the heating mode 31, the wastegate valve 13 is first opened so that the turbine wheel 7 and therefore the compressor wheel 8 are not accelerated disadvantageously and therefore do not generate charging pressure peaks disadvantageously when the variable turbine geometry 15 is closed via the minimum flow position 29 into the heating position 34.

After method step 32, the method returns to first method step 25. If the temperature of the pollutant converting device 11, and in particular the catalyst 12, continues to be below the threshold temperature, the variable turbine geometry 15 is maintained in the heating mode 34. If the temperature of the pollutant transforming device 11 exceeds the threshold temperature, the internal combustion engine system 1 is operated in the control mode 26.

When switching from the heating mode 31 into the control mode 26, the variable turbine geometry 15 is first brought into the idle position of the control mode 26 (not shown) before the wastegate valve 13 can be closed according to the idle position of the control mode 26, so that the turbine wheel 7 and therefore the compressor wheel 8 are not accelerated disadvantageously so that an unfavorable charge pressure peak results when the variable turbine geometry 15 opens from the heating position 34 past the minimum flow position 29 into the idle position. The idle position is a position of the variable turbine geometry 15 in which the guide element 16 exposes the gap 30 in order to reduce the exhaust gas back pressure.

At the heating position 34 shown in fig. 4, the guide elements 16 following one another in the circumferential direction 19 are in contact with one another. In this way, the gap 30 present between the guide elements 16 in the first position 28 is completely closed/eliminated. The same applies correspondingly to the cross section 20, so that the overall cross section is reduced, in particular in view of tolerances which are present in particular in the axial direction 18, and is eliminated, so that no exhaust gas flows toward the compressor wheel 7.

At the heating point 34, a reduced drive, in particular no drive, of the compressor wheel 8 is effected by the turbine wheel 7, so that the compressor wheel 8 throttles the fresh air flowing through the fresh air device 4. The proportion of fuel in the fresh air-fuel mixture in the combustion chamber 3 is thus increased, so that more unburned fuel component flows into the exhaust gas means 5 and is subsequently burnt there, in particular upstream of the pollutant transforming device 11 and/or in the pollutant transforming device 11. In this way, the heating of the pollutant converting device 11 is further accelerated.

As shown in fig. 3 and 4, each guide element 16/each guide vane 17 comprises a tip 35 and a tail end portion 36 remote from the tip 35, the tip 35 facing the adjoining guide element 16 in the circumferential direction 19. At the heating position 34 shown in fig. 4, the respective tip 35 is supported in the circumferential direction 19 on the surface of the trailing end section 36 of the adjoining guide element 16 facing the turbine wheel 7. In this way, by means of the guide element 16, a closed surface is formed in the circumferential direction 19 through which exhaust gases cannot flow.

Before reaching the threshold temperature of the pollutant converting device 11, in particular of the catalyst 12, in order to achieve a reduction of the pollutants present in the exhaust gas, the internal combustion engine system 1 may optionally comprise, as shown in fig. 1, a pollutant converting device 37, hereinafter also referred to as auxiliary pollutant reducing device 37, in addition to the pollutant converting device 11, and in the example shown, the pollutant converting device is arranged upstream of the pollutant converting device 11, as in the example shown, also in the bypass channel 14 downstream of the wastegate valve 13. The auxiliary pollutant reducing device 37 has a size smaller than the pollutant converting device 11. In particular, the catalyst 38 of the auxiliary pollutant reducing device 37 (hereinafter also referred to as auxiliary catalyst 38) is smaller than the catalyst 12 of the pollutant converting device 11 (hereinafter also referred to as main catalyst 12). Thus, the energy required to reach the threshold temperature of the auxiliary catalyst 38 is less than the corresponding energy required to reach the threshold temperature of the main catalyst 12. Thus, the threshold temperature of the auxiliary catalyst 38 is reached more quickly, so that the reduction of pollutants in the auxiliary pollutant reducing device 37 already starts before the threshold temperature of the main catalyst 12 is reached.

Fig. 5 and 6 each show a further exemplary embodiment of the internal combustion engine system 1. These embodiments differ from the embodiment in fig. 1 in that the internal combustion engine system 1 additionally comprises an electric machine 42 for compressing the air in the fresh air device 4. In the embodiment shown in fig. 5, the motor 42 drives the compressor wheel 8 when in operation. In the embodiment shown in fig. 6, the electric motor 42 drives, in operation, an additional compressor 43, which is integrated in the fresh air device 4 downstream of the compressor wheel 8, as shown in fig. 6. In the embodiment in fig. 6, there is also provided an additional compressor bypass 44 bypassing the additional compressor 43, which can be selectively released and blocked by means of an associated additional compressor bypass valve 45.

The internal combustion engine system 1 in the exemplary embodiment in fig. 5 and 6 can be operated according to the flowchart shown in fig. 7, which fig. 7 differs from the flowchart shown in fig. 2 in steps following method step 32.

Accordingly, in the heating mode 31, the load requirement of the internal combustion engine 2 is also taken into account in addition to the temperature of the pollutant transforming device 11 in method step 46. If the load demand is below the first threshold, the method returns to method step 25. This means that, in the event that the load requirement of the internal combustion engine 2 is below the first threshold value, the measures in method step 32 are retained and the temperature of the pollutant conversion device 11 is checked again in accordance with method step 25 and continued as described above with respect to fig. 2.

If, on the other hand, the load requirement of the internal combustion engine 2 lies between the first threshold value and a second threshold value, wherein the second threshold value is greater than the first threshold value, the electric machine 42 is activated in a method step 47 in order to compress the air using the compressor wheel 8 in the exemplary embodiment of fig. 5 and the additional compressor 43 in the exemplary embodiment of fig. 6. Thereafter, the method returns to method step 25 to check the temperature of the pollutant converting device 11 according to method step 25 and then continues as described above.

In the case of a load demand of the internal combustion engine 2 above the second threshold value, the internal combustion engine system 1 is operated in a normal cold start mode in method step 48. In the normal cool start mode, the wastegate valve 13 and the variable turbine geometry 15 are adjusted according to load requirements. This means in particular that the variable turbine geometry 15 is adjusted according to the load requirements in such a way that the guide element 16 forms a total cross section between the control minimum and the control maximum at the respective position. The motor 42 can continue to operate in particular in the exemplary embodiment shown in fig. 6. Thereafter, the method returns to method step 25 to continue the above-described process.

If the motor 42 in the embodiment shown in FIG. 6 is deactivated, i.e., the additional compressor 43 is not operating, the additional compressor bypass valve 45 is advantageously adjusted so that air flowing through the additional compressor bypass 44 bypasses the additional compressor 43.

If the internal combustion engine 2 is started and the temperature of the pollutant transforming device 11 is below the threshold value, it is preferred to bring the variable turbine geometry 15 into the heating position 34 and/or to open the wastegate valve 13 in a method step, not shown, which has been performed once each before starting the internal combustion engine 2, before this method step.

The internal combustion engine system 1 can in principle be used in any application. The internal combustion engine 1 is in particular part of a motor vehicle 39, wherein the internal combustion engine 2 is used for driving an electric drive, not shown, in addition or as a supplement.

Claims

1. A method for operating an internal combustion engine system (1), wherein the internal combustion engine system (1) comprises:

-an internal combustion engine (2) which, when operated, produces exhaust gases,

-a fresh air device (4) for supplying fresh air to the internal combustion engine (2) and an exhaust gas device (5) for discharging exhaust gases,

-an exhaust-gas turbocharger (6) comprising a compressor wheel (8) integrated in the fresh-air device (4) for compressing fresh air and a turbine wheel (7) integrated in the exhaust-gas device (5) for driving the compressor wheel (8),

an adjustable wastegate valve (13) of the exhaust-gas turbocharger (6), which in a bypass position guides exhaust gas via a bypass channel (14) around the turbine wheel (7),

-a pollutant conversion device (11) integrated in the exhaust gas installation (5) for reducing pollutants in the exhaust gas, the pollutant conversion device (11) being designed with a threshold temperature above which pollutants are reduced,

-a variable turbine geometry (15) of the exhaust-gas turbocharger (6), which variable turbine geometry comprises adjustable guide elements (16) surrounding the turbine wheel (7) in the circumferential direction (19), which guide elements (16) follow one another in the circumferential direction (19) and form at their respective locations a total cross section through which exhaust gas can flow,

wherein in a control mode (26) the pollutant transforming device (11) has a temperature above the threshold temperature, the guiding element (16) is adjusted such that the total cross section is between a control minimum and a control maximum,

it is characterized in that the preparation method is characterized in that,

when the temperature of the pollutant transforming device (11) is below the threshold temperature, operating the internal combustion engine system (1) in a heating mode (31) in which the guiding element (16) is adjusted to a heating position (34) at which the total cross section is smaller than the control minimum.

2. The method of claim 1, wherein the first and second light sources are selected from the group consisting of,

it is characterized in that the preparation method is characterized in that,

in a heating mode (34), the variable turbine geometry (15) is closed, such that the guide element (16) forms a closed surface in the circumferential direction (19) at the heating location (34).

3. The method according to claim 1 or 2,

it is characterized in that the preparation method is characterized in that,

the waste gate valve (13) is adjusted to a bypass position in a heating mode (31).

4. The method of claim 3, wherein the first and second light sources are selected from the group consisting of,

it is characterized in that the preparation method is characterized in that,

the waste gate valve (13) is opened to its maximum extent in the heating mode (31).

5. The method according to one of claims 1 to 4,

it is characterized in that the preparation method is characterized in that,

-the internal combustion engine system (1) comprises an electric machine (42) for compressing air in the fresh air device (4),

-operating the electric machine (42) in a heating mode (31) for compressing air when the load demand of the internal combustion engine (2) exceeds a predetermined first threshold.

6. The method of claim 5, wherein the first and second light sources are selected from the group consisting of,

it is characterized in that the preparation method is characterized in that,

in a heating mode (31), in case the load demand of the internal combustion engine (2) exceeds a second threshold, which is greater than the first threshold, a transition is made from the heating mode (31) to a conventional cold start mode (26), in which the wastegate valve (13) and the variable turbine geometry (15) are adjusted according to the load demand.

7. An internal combustion engine system (1) includes:

-an adjustable wastegate valve (13) of the exhaust-gas turbocharger (6), which is adjustable between a closed position and a bypass position and, when in the bypass position, leads exhaust gas via a bypass channel (14) past the turbine wheel (7),

-pollutant conversion means (11) integrated in the exhaust gas device (5) for reducing pollutants in the exhaust gas,

-a variable turbine geometry (15) of the exhaust-gas turbocharger (6), comprising adjustable guide elements (16) which surround the turbine wheel (7) in the circumferential direction (19), the guide elements (16) following one another in the circumferential direction (19) and forming at their respective positions a total cross section through which exhaust gas can flow,

-a control device (24) for operating the internal combustion engine system (1) and communicatively connected to the exhaust gas turbocharger (6),

it is characterized in that the preparation method is characterized in that,

the internal combustion engine system (1) is designed such that it is operated by a method according to one of claims 1 to 6.

8. The internal combustion engine system according to claim 7,

it is characterized in that the preparation method is characterized in that,

the internal combustion engine system (1) comprises an electric motor (42) for compressing the air in the fresh air device (4), which electric motor drives the compressor wheel (8) and/or an additional compressor (43) which is separate from the compressor wheel (8) in operation.

9. The internal combustion engine system according to claim 7 or 8,

it is characterized in that the preparation method is characterized in that,

at the heating position (34), the adjacent guide elements (16) contact each other in the circumferential direction (19).

10. The internal combustion engine system according to claim 9,

it is characterized in that the preparation method is characterized in that,

at the heating position (34), adjacent guide elements (16) are superposed on one another in the circumferential direction (19).

11. The internal combustion engine system according to claim 9 or 10,

it is characterized in that the preparation method is characterized in that,

-each guide element (16) comprises a tip (35) facing the adjacent guide element (16) in the circumferential direction (19) at the heating location (34) and a tail end portion (36) remote from the tip,

-at the heating position (34), each guide element (16) is supported with its tip (35) in the circumferential direction (19) on a trailing end portion (36) of the adjoining guide element (16).

12. The internal combustion engine system according to claim 11,

characterized in that, at the heating position (14), the tip (35) is supported on a surface of the trailing end portion (36) facing the turbine wheel (7).

13. The internal combustion engine system according to one of claims 7 to 12,

characterized in that the pollutant conversion device (11) is integrated in the exhaust gas device (5) downstream of the turbine wheel (7) and downstream of the bypass channel (14).

14. The internal combustion engine system according to one of claims 7 to 13,

it is characterized in that the preparation method is characterized in that,

-integrating an auxiliary pollutant reducing device (37) in the exhaust gas arrangement (5) such that exhaust gas flowing through the bypass channel (14) flows through the auxiliary pollutant reducing device (37),

-the secondary pollutant reducing device (37) is designed such that it requires less thermal energy than the pollutant converting device (11) to reach the operating temperature of the secondary pollutant reducing device.

15. The internal combustion engine system according to claim 14,

characterized in that the auxiliary pollutant reducing device (37) is integrated in the exhaust gas unit (5), in particular in the bypass channel (14), upstream of the pollutant converting device (11).